abstract: Extracellular rescue of sporulation mutant

[Tom Adams]

The Aspergillus nidulans fluG gene is required for production of an 
extracellular developmental signal and is related to prokaryotic glutamine 
synthetase I.

Bee Na Lee and Thomas H. Adams
Department of Biology, Texas A&M University, College Station, TX  77843
Telephone:		409-845-1468,FAX:			409-845-2891, E-mail:		Tom at bio.tamu.edu

Genes and Development (1994).  8:641-651

Abstract

	Mutations in the Aspergillus nidulans fluG gene disrupt the programmed 
induction of asexual sporulation and result in formation of "fluffy" 
colonies that are characterized by undifferentiated cotton-like masses of 
vegetative cells.  We show that the fluG mutant phenotype is suppressed when 
fluG mutant colonies are grown next to wild type colonies even if the two 
strains are separated by dialysis membrane with a 6,000-8,000 dalton 
molecular weight pore size.  fluG encodes a cytoplasmically localized 
~96,000 dalton polypeptide that is present at relatively constant levels 
during vegetative growth and following developmental induction.  Sequence 
analysis of fluG demonstrated that the C-terminal 436 amino acids predicted 
by the 864 codon FluG open reading frame shares about 28% identity with 
GSI-type prokaryotic glutamine synthetases.  We consider it unlikely that 
FluG functions in synthesis of glutamine but instead propose that FluG 
functions as a GSI-related enzyme in synthesizing an extracellular signal 
directing asexual sporulation and perhaps other aspects of colony growth.  
The relationships between fluG and other genes identified by fluffy mutants 
are discussed.
Tom Adams
Department of Biology
Texas A&M University
College Station, TX  77843
409-845-1468
Tom at bio.tamu.edu